A green corrosion inhibitor similar to polyepoxysuccinic acid is synthesized by using maleic anhydride and sodium allylsulfonate as raw material. The molecular structure is characterized by IR spectra. The efficiency of an environmental-friendly corrosion inhibitor for carbon steel in sea water is researched through method of weight loss. This new corrosion inhibitor is a mixture of multipolymer, Zn2+ and HEDP. The efficiency of the corrosion inhibitor for carbon steel in the sea water is 97.68%, when the concentration of multipolymer is 50mg/L, Zn2+ is 4mg/L, HEDP is 10mg/L. The surface of carbon steel is investigated by electron microscopy after the experiment of corrosion, and the mechanism of corrosion inhibitor is discussed.